Urban ambient particles

Atkinson RW, Fuller GW, Anderson HR, Harrison RM, Armstrong B (2010) Urban ambient particle metrics and health a time-series analysis. Epidemiology 21 501-511... 

Direct exposure of rat lung myofibroblasts to urban ambient particles from Mexico City < 10 pm in size elicited upregulation of their platelet-derived growth factor receptor a, and this effect was blocked by recombinant endotoxin neutralising protein and mimicked by lipopolysaccharide, but not vanadium, both constituents present within these samples (Bonner et al. 1998). 

One particular type of source that should be studied carefully Is entrained soil. As shown above, this Is often the greatest contributor of TSP In urban areas. As there Is so much of It present, we need to know concentrations of all measured elements quite well to make an accurate determination of the residual amounts left to be accounted for by other sources. The composition of selved soil Is often used for the soil component, but there may be considerable fractionation Imposed by entrainment, e.g., preferential selection of very fine clay mineral particles. Such fractionation has been demonstrated In the very limited studies of entrainment of particles from soil of known composition (e.g.. Refs. 21, 49). These studies can probably best be done In controlled environments such as wind tunnels. One cannot simply collect ambient particles In the countryside and consider it to be soil, as there are anthropogenic contributions even at great distances from cities ( ). There Is further confusion betwen clean, "continental" dust and "urban" dust. The latter, which Is usually collected near city streets (21, 50), typically has a composition of soil contaminated by anthropogenic emissions, especially from motor vehicles. 

TABLE 9.18 Some Difunctionally Substituted Alkane Derivatives Found in Submicron Ambient Particles in Urban Air ... 

In short, the same types of aerosol organic products have been identified both in model systems and in polluted urban ambient air and can generally be rationalized based on the oxidation of known constituents of air. The measured yields of organics in the particles can depend on the amount of particle phase available for uptake of the organic if it is semivolatile and partitions between the gas and condensed phases. This partitioning, and its dependence on the amount of condensed phase available, may be at least in part responsible for discrepancies in the yields of secondary organic aerosol reported in a number of studies. 

Assay) 1 of Fine Ambient Particles Collected at Upwind Background (San Nicolas Island), Urban (Long Beach and Central Los Angeles), and Downwind (Azusa and Rubidoux) Sites across Southern Californiaa c,d... 

In one of the first studies of the vapor-phase mutagenicity of polluted urban air, Alfheim and co-workers (1985) collected both ambient particles and vapor-phase compounds and used the Salmonella typhlmurium reversion assay. The direct activities ( —S9) of the extracts generally exceeded the promutagenicities (+ S9), and furthermore, the vapor-phase mutagenicity ranged from 0 to 88% of the total activity. 

Additionally, in two different monitoring campaigns conducted in the center of Milan, Italy, Ciccioli and co-workers (1993) reported 2-nitrofluoranthene, 2-nitropyrene, and 1-nitropyrene were the only ni-troarenes detected. Subsequently, in a comprehensive study of the atmospheric formation and transport of 2-nitrofluoranthene and 2-nitropyrene, they established their presence and levels in ambient particles collected at sites located in urban, suburban, forest, and remote areas in Europe, Asia, America, and Antarctica (Ciccioli et al., 1996, and references therein see also Ciccioli et al., 1995). 

Fig. 2a-c Typical urban ambient air particle number size distribution measured in Brisbane... 

Kaupp H, McLachlan MS (2000) Distribution of polychlorinated dibenzo-P-dioxins and dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) within the full size range of atmospheric particles. Atmos Environ 34 73-83 Kim K-S, Masunaga S (2005) Behavior and source characteristic of PCBS in urban ambient air of Yokohama, Japan. Environ Pollut 138 290-298... 

Mauad T, Rivero DHRF, de Oliveira RC et al (2008) Chronic exposure to ambient levels of urban particles affects mouse lung development. Am J Respir Crit Cate Med 178 721-728 Mazzarella G, Ferraraccio F, Prati MV et al (2007) Effects of diesel exhaust particles on human lung epithelial cells An in vitro study. Respir Med 101 1155-1162 McClellan RO (2000) Particle interactions with the respiratory tract. In Gehr P, Heyder J (eds) Particle-lung interactions, 1st edn. Marcel Dekker, New York Mills NL, Ttimqvist H, Gonzalez MC et al (2007) Ischemic and thrombotic effects of dilute diesel-exhaust inhalation in men with coronary heart disease. N Engl J Med 357 1075-1082 Mills NL, Robinson SD, Fokkens PHB et al (2008) Exposure to concentrated ambient particles does not affect vascular function in patients with coronary heart disease. Environ Health Perspect 116 709-715... 

Evidence has grown over the last decade, that urban airborne particles at ambient concentration levels common in many cities in Europe, America and Asia exert adverse effects on human health. Short- or long-term exposure to particulate matter (measured as PMio or PM2.5) is associated with an increase risk of cardiovascular and respiratory morbidity and mortality. Collectively the toxicological and epidemiological studies provide sufficient evidence that a causal relationship is likely to exist between exposure to ambient concentrations of PMjo or PM2.5 and specific human morbidity (exacerbation of chronic bronchitis, asthma or coronary heart disease) and premature deaths. 

The oxygen burst of monocytes induced by ambient air particles (with the exception of oil fly ash particles) was less than the response elicited by polymorphonuclear leucocytes (Prahalad etal. 1999). The luminol-enhanced chemiluminescence response of polymorphonuclear leucocytes separated from heparinised human blood was generally increased with all washed particles, with oil fly ash and one urban air particle showing statistically significant (P <0.05) differences between dHjO-washed and unwashed particles. The luminol-enhanced chemiluminescence activity in polymorphonuclear leucocytes induced in post particles... 

On the other hand, the exposure risk of ClPAHs and PAHs in the air was also calculated using the individual REPeap and corresponding mean concentrations obtained from ambient particles in Japanese urban air [16]. The calculated TEQ concentrations of total ClPAHs and PAHs were 2.95 and 650 pg-TEQ/m, respectively, indicated that the contribution of ClPAHs to PAHs was less than 1 %. 

A central hypothesis derived from this data is as follows Ambient air particles are complex mixtures with intrinsic toxicity. In concert with preexisting inflammation, particulate exposure results in stimulation of lung receptors and immune cells, release of reactive oxygen species (ROS), and induction of pro-inflammatoiy mediators that lead to local and systemic effects, which ultimately account for the epidemiological associations between adverse health effects and particulate air pollution. Hypothetical mechanistic pathways by which inhalation of ambient particles in urban air may lead to morbidity and mortality are outlined in Figure 1. 

When a liquid or solid substance is emitted to the air as particulate matter, its properties and effects may be changed. As a substance is broken up into smaller and smaller particles, more of its surface area is exposed to the air. Under these circumstances, the substance, whatever its chemical composition, tends to combine physically or chemically with other particles or gases in the atmosphere. The resulting combinations are frequently unpredictable. Very small aerosol particles (from 0.001 to 0.1 Im) can act as condensation nuclei to facilitate the condensation of water vapor, thus promoting the formation of fog and ground mist. Particles less than 2 or 3 [Lm in size (about half by weight of the particles suspended in urban air) can penetrate the mucous membrane and attract and convey harmful chemicals such as sulfur dioxide. In order to address the special concerns related to the effects of very fine, iuhalable particulates, EPA replaced its ambient air standards for total suspended particulates (TSP) with standards for particlute matter less than 10 [Lm in size (PM, ). 

Urban aerosols are complicated systems composed of material from many different sources. Achieving cost-effective air particle reductions in airsheds not meeting national ambient air quality standards requires identification of major aerosol sources and quantitative determination of their contribution to particle concentrations. Quantitative source Impact assesment, however, requires either calculation of a source s impact from fundamental meteorological principles using source oriented dispersion models, or resolving source contributions with receptor models based on the measurement of characteristic chemical and physical aerosol features. Q)... 

Ambient aerosols, particularly those with diameters less than 3pm, are a serious pollution problem. Carbonaceous material is a major component of the fine particle concentration (10 and has undergone extensive study in the past few years (, ) in large part because of the concern that these particles play an Important role in urban haze and community health. 

Throughout this chapter, we cite examples of the use of the NIST Standard Reference Material SRM 1649, which is referred to as Air Particles or Urban Air Particulate Matter, (a) to validate analytical procedures for determination of PAHs and PACs in samples of complex mixtures of particulate matter in ambient air and (b) for laboratory intercomparisons of methodologies for bacterial bioassays and bioassay-directed fractionations of organic extracts of such mixtures (e.g., see Claxton et al., 1992a Lewtas et al., 1990a, 1992 and May et al., 1992). 

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